Signalosomes are large supramolecular
protein complexes that undergo clustering (oligomerisation or polymerisation) and/or
colloidal phase separation
Phase separation is the creation of two distinct phases from a single homogeneous mixture. The most common type of phase separation is between two immiscible liquids, such as oil and water. Colloids are formed by phase separation, though n ...
to form
biomolecular condensates that increase the local concentration and
signalling
In signal processing, a signal is a function that conveys information about a phenomenon. Any quantity that can vary over space or time can be used as a signal to share messages between observers. The ''IEEE Transactions on Signal Processing'' ...
activity of the individual components. They are an example of
molecular self-assembly
In chemistry and materials science, molecular self-assembly is the process by which molecules adopt a defined arrangement without guidance or management from an outside source. There are two types of self-assembly: intramolecular and intermole ...
and
self-organisation
Self-organization, also called spontaneous order in the social sciences, is a process where some form of overall order arises from local interactions between parts of an initially disordered system. The process can be spontaneous when suff ...
in
cell biology
Cell biology (also cellular biology or cytology) is a branch of biology that studies the structure, function, and behavior of cells. All living organisms are made of cells. A cell is the basic unit of life that is responsible for the living and ...
.
Examples
Wnt signalosome: Transduction of
Wnt signals from the plasma membrane depends on clustering of
LRP6 receptors with Dishevelled (
Dvl) proteins to recruit the
Axin
Axin-1 is a protein that in humans is encoded by the ''AXIN1'' gene.
Function
This gene encodes a cytoplasmic protein which contains a regulation of G-protein signaling (RGS) domain and a dishevelled and axin (DIX) domain. The encoded protei ...
complex for inactivation.
B-cell receptor (BCR) signalosome: The
B-cell receptor (BCR) binds antigen and undergoes clustering to induce signal transduction.
T-cell receptor (TCR) signalosome: Antigen presentation to T-cells is recognised by the
T-cell receptor (TCR), which initiates clustering and activation of downstream signalling to induce T-cell responses.
: Catalyses the hydrolysis of
NEDD8 protein from the Cullin subunit of
Cullin-RING ubiquitin ligases (CRL). Therefore, it is responsible for CRL
deneddylation – at the same time, it is able to bind deneddylated cullin-RING complex and retain them in deactivated form. COP9 signalosome thus serves as a sole deactivator of CRLs.
RIP1/RIP3 Necrosome: A signalling complex involved in necrotic cell death.
s: The
AIM2
Interferon-inducible protein AIM2 also known as absent in melanoma 2 or simply AIM2 is a protein that in humans is encoded by the ''AIM2'' gene.
AIM2 is a cytoplasmic sensor found in hematopoietic cells that recognizes the presence of double-stra ...
and
NLRP3 inflammasomes are filamentous assemblies that elicit host defense inside cells by activating caspase-1 for cytokine maturation and cell death.
References
Protein complexes
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